High frequency tuner



June 27, 1939. p WARE I HIGH FREQUENCY TUNER Filed Aug. 11 1936 5 Sheets-Sheet l INVENTOR Paul Wan ATTO R N EY June 27, 1939. P WARE 2,163,647

HIGH FREQUENCY TUNER Filed Aug. 11, 1956 3 Sheets-Sheet 2 7 33 if 7a 79 H 1 I I a i 1 iii INVENTOR HIHIHmm W BY fwm I a A m k ATTORNEY 3 Sheets-Sheet 3 Ki E wm NS MK m \u i R m E I I a Y E WN o E w E W W E E W m Q. W .E, I W I m I Ll i, v Ll I l L a a E I E E P mw\ Q H E E I W m June 27, 1939. P R

HIGH FREQUENCY TUNER Filed Aug. 11, 1956 Patented June 21. 1939 PATENT OFFICE.

HIGH FREQUENCY TUNER.

Paul Ware; Indianapolis, Ind., animal to P. B.

Mallory & 00., Inc., Indianapolis, Ind., a cor rotation of Delaware Application August 11, 1938, Serial No. 95,382

. ll'claims.

This invention relates to the reception of ultra high frequency signals.

An object is to provide an efficient means for receiving such signals.

Another object is to provide an improved inductive tuning method for tuning the resonant circuits required in the reception of ultra high frequency radio signals.

A still further object is to provide an efficient combination of tuning means suitable for the reception of ultra high frequency, high frequency and broadcast signals.

Gther objects of the invention will be apparent from the following description and accompanying drawings taken in connection with the appended claims.

The invention comprises the features of construction, combination of elements, arrangement of parts, and methods of manufacture and operation referred to above or which will be brought out and exemplified in the disclosure hereinafter set forth, including the illustration in the drawings.

In resonant tuning systems arranged for the reception of widely divergent signal frequencies and having switching means for changing the circuit connections from one frequency band to another, there is the problem of overcoming a certain amount of undesirable inter-action between the circuits in use and those not in use in each switch position. This problem of circuit inter-action is greater on high frequencies and presents a serious problem in the ultra high frequency portion of the radio spectrum.

In my co-pending applications S. N. 31.823, filed July 17, 1935; Serial No. 94,927, filed August 8, 1936, and Serial No. 94,928, filed August 8, 1936, are described means for tuning radio circuits by the use of variable inductances. With such tuning arrangements it is possible to cover wider frequency bands for each switching position and more efficient high frequency and ultra high frequency performance may be obtained than with the now customary condenser tuned arrangements.

The present invention relates to improved means for inductive tuning wherein the undesirable eifect of coupling between circuits in use and those not in use has been substantially eliminated. The invention also contemplates improved structure and circuit. means for tuning high frequency and ultra high frequency signal systems.

In the drawings: Figure 1 is a side view, partly in section, of a double coil per section inductive tuning device embodying features of the invention;

Fllgure 2 is a section on the line 2-2 of Figure Figure 3 is a side elevation of a'double coil in- 5 ductive tuner having a double contactor arrangement for each coil;

Figure 4 is a section .on the line' 4-4 of Figure Figure 5 is a detail of the double contactor of 10 Figures 3 and 4;

Figure 6 is an end detail view of the double contactor;

Figure 7 shows a modification of the two coil per section arrangements of Figure 1;

Figure 8 is an end view of the structure of Figure 'l; t

Figure 9 is a sectional view of a tapped coil; and

Figure 10 is 'a top view of the tapped coil arrangement of Figure 9.

While a preferred embodiment of the invention is described herein, it is contemplated that considerable variation may be made in the method of procedure and the construction of parts without departing from the spirit of the invention. In the following description and in the claims, parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit. 7

Referring to the drawings, Figures 1 and 2 show a two section double coil inductive tuner structure intended for the tuning of broadcast, high frequency and ultra high frequency radio signals, One of the sections may be used as the antenna input tuning unit and the other as the local oscillator tuning unit.

The radio frequency spectrum may be considered as divided as follows: broadcast frequencies from .54 to 2.0, high frequencies from 2.0 to 18.0 and. ultra high frequencies from 18.0 to 60.0 plus megacycles per second.

The casefor the tuner structure comprises a bottom plate "I, front and rear end plates ii and i2, partition I4 and has a cover l3 fitted over the edges of the end plates and partition and anchored to the bottom plate ill by anchoring plate 60, whereby the entire unit is enclosed and electrically shielded.

Shaft I 5 is mounted to rotate in bearings l9, is secured in end walls H and I2 and supports two large variable inductance coils ii for rotation about the coil axis. Coils it are wound on cylindrical forms I l which are supported from the shaft by insulating end discs 40 pressed into the left ha d ends of forms H, H. End discs 48 are attach d to the hubs l8, l8, which are in turn fixed to shaft I by set screws.

A pair of smaller coils 28, wound on forms 2|, 2B of Bakelite or other suitable insulating material are mounted for rotation alongside the coils 98.

The coil forms 2|, 2| are operatively connected It. Shaft 27 connects the two small coil forms together to rotate as a unit the shaft passing through the partition l5.

All four coil forms I! and 2| are grooved and the windings i8 and 20 may be silver plated hard copper wire. All four coils have the same numberv of turns and the mechanical arrangement is such that the turns of the windings on the smaller coils-are directly alongside the windings'on the larger coils and the axis of rotation of the smaller coils is parallel to shaft l5.

A split gear 28 is attached to the right hand end of shaft l5 (as shown in Figure 1) and a gear 29 is attached to the outer end of shaft 25 and insulated therefrom by insulating hub 3i, gears 28 and 29 being geared together. Split gear 28 is provided with a tension spring 38 to minimize the back-lash between gears 28 and 29 during operation, in a well-known manner.

Contact bars 32 of channel shaped pressed metal are mounted parallel to the coil sides. One of bars 32 is shown in the left hand section in Figure 1 mounted on end plate II and partition M by integral end flanges on the bar. A similar bar 32 (not shown) is mounted in-the right hand section.

A moving contactor assembly comprising an elongate frame 33, a pair of grooved insulating trolley wheels, 34, 34, a channeled contact spring 35 and a pair of double-nibbed contact springs 31 and 38 is held between bar 32 and the coil assemblies in each section.

B The spring member 35 may be of phosphor bronze having bifurcated and beaded ends as shown. Spring 35 is attached to the frame 33 by a rivet and is additionally kept in place by ears 36 that are bent over the frame 33. The phosphor bronze spring member 35 makes sliding contact with contact bar 32 and supplies the needed spring tension between the contact bar 32 and the member 33. The channeled contact portions of spring 35 also prevent any undesirable tudinal edge of frame 33.

Groovedtrolley wheels 34, 34 are provided with spindles which rest in bearing portions pressed The preferred design of the contact springs 31 and 38, their most suitable pressure on the wire of the coil and their preferred position of tangency with respect to the wire of the coil on which they slide is more fully described in my co-pending application Serial No. 94,927, filed August 8, '19 c The contactor assembly in the present instance spans two coils, namely 68 and 20, with a trolley wheel and a contact spring riding on each. The contactors 3i and 38, the frame 33, and the spring 35 form an electrical connection between the conductors of both the coils and the contact bar 32 which is grounded to the metal case of the unit.

Attached to the insulating end disc 48 of each of the large forms ii is a silver faced end ring member M which is supported in spaced relation to the insulating end disc ill by three integral legs. One leg 62 of the ring ll is long enough to go out to the periphery of the coil form ii and the left hand end of each large coil winding 15 (as seen in Figure 1) is attached thereto at point 33 (Figure 2). The ends of the two arms of a U-shaped contact member 64 ride on the face of each end ring 69. The contact member dd is eyeleted to insulating strip-i5 which is supported from and in spaced relation to end plate it (or partition it) by the spacer mountings 38.

The hub it on shaft 35 is likewise silver faced and forked ground spring contactor 4? slides on the silver face thereof. The forked contact spring ill for the left hand section is riveted to end plate l i and for the right hand section is riveted to partition i i. The contact spring members Q5 and d7 may be of phosphor bronze and preferably may be provided with contact facings of low friction and low resistance where they make contact with the slip rings. The right hand end of the conductor of each of the large coils it passes through the'inside of its form I! to its respective hub 8 and is electrically connected thereto. The right hand end of the coils 5 is thereby grounded to the case through hub l8 and contact'spring 67 so that the right hand end of each of the large coils is at approximately the potential of the case. The left hand end of each of the large coils I6 is connected through the slip ring 4| and spring contactor 44 to the tab terminal 48 which thus provides a connecting terminal for the coil I6, the case of the unit serving as the other terminal. These terminals may be associated with end inductances, fixed capacities and other components to form resonant antenna, in-' ter-stage or oscillator circuits for radio systems as outlined in my co-pending applications Serial Nos. 31,823 filed July 17, 1935, and 94,928, filed around and anchored to pins 53 in the coil forms 2| and then connected, respectively to the rings 49, 50, 5| and 52. The rings 50 and 52 at the right hand ends of the respective coils 2|l are grounded to 'the case by forked sliding contact springs 54 similar in design to spring 4'! and riveted to partition I4 and end plate l2, respectively. Insulating spacers 58, 58 prevent lateral play in the small coil assembly.

Forked springs 55, 55 make'sliding contact with rings 49 and 5| at the left hand ends of the respective coils 20. Springs 55 are secured by eyelets to insulating strips 56 which are spaced away from the end plate II and partition l4, respectively in the same manner that contact spring 44 is spaced, as was described above. Y Springs 58 are provided\ with tabs 51 which serve as connecting terminals to the ends of coils 20, the case being the other terminal.

Coils I6 and 2|! may be connected in separate tuning circuits for selective or independent use in tuning over different frequency ranges but are mechanically connected together by gears 28 and 29 for common control by tuning knob 39. By means of the customary wave change switch employed in radio receiving circuits either the larger coils or the smaller coils may be utilized with suitably proportioned and arranged circuit components so as to operate over the desired predetermined frequency range. Coils l8 may be so proportioned. as to enable tuning over the broadcast and high frequency ranges of radio signals with two switching positions and small coils 20 may be proportioned to enable tuning over the ultra high frequency range when the circuits are connected to the small coils in a third switch position. The natural period of the coils 20 should be outside the ultra high frequency tuning range. a

The knob 39 may be attached to either end of shaft I5. When the knob is rotated to the right or left it will cause both sets of coils to rotate at equal angular speeds and with a gear ratio of 1:1, as shown, the trolley-wheels 34 and their associated sliding contacts 3! and 38 will travel from one end of the coils to the other in unison. The winding direction of the smaller coils Zll, 20 is, of course, opposite to that of coils |8, |8[

' FiguresB, 4, 5 and 6 show a second method of satisfactorily arranging a variable inductance tuner so that it may be operated on ultra high frequency or broadcast frequency as desired without the ultra high frequency range suffering from the effects of undue coupling with the unused part of the coil. Coils l8, l6 are similar to coils I6 of Figures 1 and 2 and are wound on similar forms i1, IT. The coil's'may be so proportioned as to enable the tuning of the broadcast and the high frequency ranges. Silver faced slip rings 4|, 4| and hubs l8, l8 and the contacting springs 44, 44 and I1, 41 are similar to like numbered parts in Figures 1 and 2. Also the shaft l5, bearing assemblies l9, l9, the knob 39, as well as the 'base plate i0, anchoring spreader plate 60, front end plate rear end plate l2, partition 14 and cover I! are also the same as like numbered parts in Figures 1 and 2. The

two section unit of Figures 3 and 4 may be connected and operate in the manner described for the arrangement of Figures 1 and 2.

In the arrangement of Figures 3, 4, 5 and 6,

the sides of the coils. Trolley wheels I8, 18 ride along the conductor of the coil and are mounted on spindles which have a running fit in the contactor frame 15. The springs l1, 11 are in compression and hold the member 15 in uniform reiati'm to the coil. The double nibbed contactor spring 80 is attached to the member 15 and positioned between the trolley wheels l8, 18 so that the two nibs will slide with light pressure along the wire of the coil. This contactor carriage assembly thus far described is generally similar to that described in my co-pending application Serial No. 94, 927, filed August 8, 1936.

The contactor carriage frame I! has a projecting table portion 19 more clearly indicated in Figure 5, this table portion carrying auxiliary double nibbed contactor spring 8|. An upstanding post 82 is riveted to the mid-portion of 10 spring 8|.

An eccentric shaft 83 is pivoted in thefront plate II and rear plate l2 as indicated in Fig. 3, andmay be turned so as to be in a position indicated in Figure 4 where the eccentric portion is 15 to the left of the axis and the shaft is just out of contact with the post 82. With the eccentric shaft in this position contact spring 8| slides on the conductor of its coil l8 several turns away from the point of contact of contact spring 88 with the coil conductor. If eccentric shaft 88 is rotated by knob 84 to about 180 degrees from the position just described, the post 82 is deflected so as to raise auxiliary contact spring 8| of! the wire of the coil l8, as shown in Figure 6.

It is to be understood that the contactor assemblies just described are the same for both coils of the unit shown in Figure 3, the rod 83 having its eccentric portion extending from one end of the unit to the other and causing similar 30 lifting or lowering of the auxiliary contacts 8| for both of the coils Hi, IS in unison when knob 84 is turned. There is no central bearing for eccentric rod 83, there being provided a clearance hole in the partition H in which it may freely 35 turn without touching. It has been found that the pressure and hence the friction existing between post 82 and the eccentric rod 83 is lightenough to avoid noticeable turning friction to the coil unit when operated by the knob ll.

The arrangement of Figures 3 to 6 provides 'for satisfactory ultra high frequency tuning with the same variable inductance coil as is used for broadcast and high frequency tuning. This is made possible by the use of the auxiliary contacting spring. When this is in contact with the coil, the natural frequency of the unused part of the coil is considerably raised particularly when the main contactor 80 is near the high frequency end of its travel (the left end in Figure 3). To avoid unnecessary absorption of energy when operating the coils in circuits for tuning over the broadcast or high frequency ranges, it is desirable to raise the auxiliary spring 8| off the coil. When ultra high frequencies,

such as frequencies higher than 18 or 20 megacycles are to be tuned, the auxiliary spring is lowered to make contact with the coil to raise its natural frequency. I have found that for a threeinch diameter, two-inch long coil of thirty-five turns a satisfactory operating position for the auxiliary contactor 8| is five ,fuil turns away from themain sliding contactor 80. When using such an assembly the full thirty-five turns of coil |B may be tuned through on the broadcast and high frequency ranges where the auxiliary contactor 8| is raised. When the contactor 8| is in its lowered position, however, and the ultra high frequency range is being covered only 30 turns may be tuned through without one of the conta'ct springs running off the end of the coil.

Figures 7 and 8 show a modification of the double coil per section inductive tuner of Figure 1 wherein the smaller coil ||l| mounted on form if has less turns than the larger coil l8 employed in the same section. Each smaller coil is of the same length as its associated larger coil, and the two coils in each section are mounted side by side as with the assembly of Figures 1 and 2. The moving contact member ii!!! is similar to the member 33 shown in Figure 1 except that the trolley wheels 3! riding on the smaller coils iii! are angularly oriented to the contactor frame I to enable the grooves in these wheels to assume a position more nearly parallel to the conductors of the smaller coils on which they ride.

The size of conductor for coil it! may be larger than that of coil it, as shown in Figure 7. The double nib spring contact memlxer Hi3 attached to frame ind makes continuous sliding contact with the conductor of coil iiii. Contact spring 903 may be of a slightly offset design as shown in dotted lines-in Figure 7 or may be oriented to be parallel with the groove of the trolley wheel and the conductor of coil iili.

It will be seen in Figure 7 that for equal length of large and small coils Where the number of turns on the smaller coils is less than the number of turns on the larger coils, it is necessary to pro-- vide a gear ratio of greater than 1 to 1 in order the stub shaft Hi6 at the end of the small coi l assembly. Except as indicated the remaining parts of Figures '7 and 8 and the operation of the modified device are similar to what is described for Figures 1 and 2.

The fewer number of turns of the smaller coils lili, Iiil of Figure 7 has the advantage of afl'ording a wider ultra high frequency band spread.

This increase in band spread is very desirable in tuning these very high frequencies.

In the arrangement of Figure '7, as well as that of Figure 1, there may be certain turn combinations of the larger and smaller coils where the presence of the larger coils may cause an absorption loss at some point within the ultra high frequency range where the tuning is done with the smaller coils. The presence of the grounded contactor 31 on the larger coil decreases this loss. In some instances the grid end of the larger coils may also be grounded as at tab 48 (by a switching arrangement, not shown) when operating the smaller coil on ultra high frequencies.

With the arrangement of Figures '7 and 8 where the gear ratio is other than 1 to l, the larger gear may, if desired, be hooked'up with a dial mechanism for coarse tuning.

Figures 9 and 10 show still another modification of the inductive tuner suitable for tuning I ultra high frequencies as well as broadcast and other frequencies and embodying a tapped coil.

[6a. The form I50, upon which coil I 6a is wound, is provided with an opening ll in its face. Con- -ductor I53, inside the coil form, is connected to the conductor of coil i6a at a point I52 on the underside of one of the turns of coil lia overlying hole l5l. The connection may be made by welding or if untarnishable materials are used, it may be made by laying a fine conductor for a short distance along the groove in which the conductor of coil lid is to be wound and then winding the coil I to into the groove. The conductor I53 is connected to a ring I54 inside the coil form,

the ring I54 being clamped by nut I55 on threaded hub I56 against the inside face of insulating end disc w. A ground sleeve I5! is secured to shaft I 5 and surrounded by the insulating sleeve I58 about which hub I56 is secured. The outer face of the hub is preferably silvered and the spring contact member i59 makes contact therewith.

The right hand extremity of coil iGa (not shown in Figures 9 and i0) is grounded by conductor Hi9 inside the coil form to sleeve H7, attached to shaft it by set screw iti. Two such tapped coil and hub assemblies may be used in the case mounting described above for Figures 1 or 2; The grounding contact spring M32 is riveted to the right hand face of the front end plate or the right hand face of central partition depending upon whether it is the left hand or the right hand coil respectively.

It is to be understood that the coil ida of Figures 9 and has a sliding contactor assembly mounted in cooperation therewith in the manner heretofore described. This single contactor assembly may preferably be like that shown in my co-pending application Serial No. 94,927, filed August 8, 1936.

it has been found that if coil ita has three inch diameter and a winding length of approximately two inches and has thirty-five turns in all, the groundable tap connection I52 suitably may be eight full turns in from the left end of the coil it which is usually the grid end when connected in tuning circuits. Satisfactory ultra high frequency performance may then be obtained therewith by grounding the tap connection through the contactor spring I59 to the frame (as by a switch, not shown). The ultra high frequency range is then continuously tunable through these eight turns between the left end of the coil and the tap. When the tap connection is not grounded, the coil in has similar characteristics to the coils i6, shown in Figures 1 and 2, and is satisfactory for broadcast and high frequency performance. This construction may have the advantages of greater economy for some applications.

The combination ultrahigh frequency, broadcast and high frequency variable inductance combinations described above may either be constructed in.two section units as shown in the drawings, or they may be constructed and-operated as single units or in three or more section units as may be desired.

' not desired to be limited thereby but it is intended to cover the invention broadly within the spirit and scope of the appended claims.

What is claimed is:

1. A variable inductance device comprising a pair of inductance coils each arranged for rotation about its axis, one of said coils having a greater number of turns per unit length than the other, a contact assembly, means to move said contact assembly along both said coils in contact therewith and means coupling said coils together mechanically for rotationin unison at angular speeds proportional to the number of turns per unit length thereon.

2. A variable inductance device comprising a pair of inductance coils arranged side by side for rotation about parallel axes, one of said coils having a greater number of turns per unit length than the other, a contact assembly, means to move said contact assembly along both said coils in contact therewith, and means coupling said coils together mechanically for rotation in unison at angular speeds proportional to the number of turnsper unit length thereon.

3. A variable inductance device comprising two rotatable inductive coils, each comprising a bare conductor formed into a helix, a contact, individual to each of said coils and connected to an end of its respective coil, and means guiding said contacts along the conductors of their respective coils whenever said coils are rotated, mechanical means for rotating said two coils in unison, and individual terminal means for each coil whereby each coil may be used independently of the other as the variable element of a tuning circuit, the inductive change per turn of one of said coils being greater than the inductive change per turn of the other of said coils during their said rotation, said contact engaging said coil of greater inductance change per turn serving to limit absorption of energy from the said other coil during use of said other coil.

4. A dual rotatable coil variable inductance device for tuning resonant radio circuits, comprising a pair of inductance coils, the inductance per turn of one of said coils diifering from that of the other of said coils, a moving contactor, means to rotate said coils in unison and to move said contactor along both of said coils in contact therewith to vary the inductance thereof, and means grounding one end of each of said coils.

5. A dual coil variable inductance device for tuning resonant radio circuits comprising a pair of multi-turn inductance coils formed of bare conductors, means supported said coils side-byside for rotation about parallel axes,. common control means for rotating said coils in unison,

a common contactor assembly engaging the conductors of both of said coils and means guiding said contactor assembly along the sides of said coils and along said conductors when said coils are rotated in unison, one of said coils being of smaller diameter than the other, said control means rotating said coils at relative angular speeds which are proportional to the number of turns per unit length on said coils. 6. A variable inductance device comprising tw bare conductors formed into two coils of unlike diameters, means mounting said coils for rotation about parallel axes, common drive meansfor rotating said coils in unison, a guide mounted adjacent and in parallel to the sides of said coils, a contactor assembly mounted between said guide and the sides of said coils, said assembly comprising a rigid frame member and two grooved insulated wheels pinioned therein, said wheels being guided respectively by the conductors of said coils, a resilient spring between said frame member and said guide urging said frame member toward said coils, each of said wheels maintaining the said carriage member at a constant spaced relation from the coil on which said wheel is guided and two spring contactors attached to said frame member each slidably pressing on the conductor of one of the said coils.

7. A variable inductance device for ultra-high frequency and lower frequency operating ranges comprising a rotatable inductive coil and a contactor movable along the coil conductor in contact therewith for varying the effective inductance of said coil, means for short-circuiting the unused part of said coil to raise the natural frequency of said unused part above the range of lower frequency operation, and means for dividing said unused part into at least two sections to additionally raise said natural frequency above said ultra-high frequency operating range, and independently actuated means for rendering said dividing means inoperative.

8. A continuously variable slide-wire inductance device comprising an inductance coil formed of a bare conductor, a contact, tuning means to move said contact along the conductor of said coil in contact therewith, said contact dividing said coil into a used and an unused part, the movement of said contact varying the inductance of said used part, an auxiliary contact engaging the unused part for changing the natural frequency of the unused part, and means actuated independent of the tuning means for rendering said auxiliary contact ineffective for changing the natural frequency of the unused part.

9. A variable inductance device comprising a bare conductor formed into a coil, a pair of contactors, means for simultaneously moving said contactors along the conductor in contact therewith at spaced points thereon, means electrically connecting both of said contactors to one end of said coil, and independently controllable means for opening one of said contactor connections.

10. A variable inductance device comprising a bare conductor formed into a coil, a pair of contactors, means for simultaneously moving said contactors along the conductor in contact therewith at spaced points thereon, means electrically connecting both of said contactors to one end of said coil, and independently controllable means for opening the connection of the one of said contactors nearest said one end of the coil.

11. A variable inductance device comprising a bare conductor formed into a coil, a contactor, means for moving said contactor along the conductor in contact therewith, terminal means at the first and second ends of said coil, means connecting said contactor-to the second end of said coil, 9. fixed tap connection at an intermediate point on said coil connecting said point to the second end of said coil, whereby said variable inductance device is tunable over a predetermined range of frequencies by moving said contactor along said conductor between said tap connection and said first end of said coil and means for opening said tap connection whereby said variable inductance device is tunable over a different predetermined range of frequencies by moving said contactor along said conductor between said first and second ends of said coil past said tap.

PAUL WARE. 

